Okay, so the argument you are trying to further is the benefits of a decentralized government, yes? That'd be most likely on the aff of that resolution. It isn't a very good argument, though, just FYI.

One would assume that it is affirming jury nullification as a check on a strong centralized power. In other words, as a government moves toward being overly centralized, it sucks up power and begins to, being too far removed from the citizens, pass unjust edicts to govern those citizens.

Jury nullification not only allows citizens to nullify any of these unjust edicts at will, but also provides a deterrent to a government who wants to pass them by ensuring that negative attention will be drawn to those edicts, which would highlight a government's attempt to centralize and citizens would intervene.

I assume the typical evidence used would be like the Southern trials where members such as the KKK were released due to jury nullification. However, the counter would probably be some Western sheriff that broke the rules a bit to ultimately put away a convict.

You can either have a decentralization argument, or basically a justification on the ideal that people should not be dominated by fear of breaking a law, but instead should be more focused on doing what is "morally correct".

Again, being "dominated by fear of breaking the law" isn't really a strong aff argument, just like decentralization isn't. I hesitate to release what I've actually found, or obviously what my kids have found, since stuff of mine has been stolen from DDO and run in rounds before in my area, but in terms of meeting the aff burden, there are plenty of really good arguments centering around meeting community norms and upholding the democratic process that you should look into.